1. Field of the Invention
The present invention relates to an ink-jet recording apparatus which discharges ink from a recording head to form images on a recording medium, and a cap for an ink-jet recording apparatus for maintaining discharging of ink from nozzles of the recording head in a suitable state. In addition to common printing apparatuses, the present invention can be applied to photocopiers, facsimile apparatuses having communication systems, word processors or the like having printing units, and further to industrial recording equipment which is combined with various processing devices.
2. Description of the Related Art
Recording apparatuses having the functions of printers, photocopiers, facsimile devices, etc., and recording apparatuses used as output devices of complex electronic equipment including computers, word processors, or the like, or workstations, are configured to record images based on image information on recording media such as paper, thin plastic plates, or the like.
Of such recording apparatuses, recording apparatuses which use the ink-jet method (i.e., ink-jet recording apparatuses) perform recording by discharging ink onto a recording medium from a recording head serving as the recording means. Such ink-jet recording apparatuses have the following advantages.
The recording head can be readily reduced in size, fine images can be recorded at high speeds, recording can be performed on plain paper with no special processing required, and the running cost is low. Being a non-impact method, there is little noise, and moreover color images can be readily recorded using inks of multiple colors. Also, recording can be performed at even higher speeds using line-type ink-jet recording apparatuses which use line-type recording heads with a great number of nozzles arrayed in the width direction of the recording sheet.
Particularly, with ink-jet type recording heads which discharge ink using thermal energy, a high-density fluid channel array (nozzle array) made up of electro-thermal converters, electrodes, fluid channel walls, ceiling, etc., formed on a substrate, can be realized by semiconductor manufacturing processes such as etching, vapor deposition, sputtering, and so forth, thereby facilitating even further reduction in size.
With ink-jet recording apparatuses, images are recorded on a recording medium by discharging ink from the nozzles according to electric signals. With such ink-jet recording apparatuses, in the event that air intrudes into the nozzles or the viscosity of the ink increases or so forth due to drying, the nozzle becomes incapable of discharging ink, and ink droplets according to the electric signals cannot be discharged from the nozzles.
As one method for recovering from such a state wherein the nozzle is incapable of discharging ink, there is the suctioning method (suctioning recovery) wherein ink which does not contribute to recording to the image is suctioned and removed from the tip of the nozzle. In this suctioning recovery, a technique for generating negative pressure for suctioning ink so as to suction the ink is normally used. As one such arrangement, there is a tube pump wherein negative pressure is generated within a pump tube by rotating a pump roller in contact with the pump tube, i.e., by working with the pump.
An example of a suctioning recovery device using such a tube pump is a configuration wherein a suctioning opening and an atmosphere communicating opening are formed within a cap which is capable of capping the recording head, and a tube pump is connected to the suctioning opening, while a valve rubber opened and closed by a valve lever is connected to the atmosphere communicating opening. The cap and tube pump are driven relating to the rotating direction of a PG motor, and the valve lever is driven according to the rotating direction of a recording medium discharging roller by an LF motor.
That is to say, first, once the discharging roller is reverse rotated, the valve lever opens the valve rubber so that the atmosphere communicating opening is opened. Subsequently, forward rotation of the PG motor brings the cap into contact with the face of the recording head upon which are formed the ink discharging orifices, thereby capping the recording head. At this time, the tube pump is driving forwards by forward driving of the PG motor, but forward driving does not bring the pump roller into contact with the pump tube, so there is no negative pressure generated.
Subsequently, the discharging roller is rotated forwards, so the valve lever closes the valve tube, and the atmosphere communicating opening is closed. Further, reverse rotating of the PG motor drives the tube pump reverse. Thus, the pump roller rotates while being pressed against the pump tube, working the pump tube to generate negative pressure. This generated negative pressure is introduced from the suctioning opening into the cap. At this time, the cap has capped the recording head and the atmosphere communicating opening is closed by the valve rubber, so viscous ink no longer suitable for recording, bubbles, etc., are suctioned out from the ink discharging orifices of the recording head by this negative pressure introduced within the cap. Further, the viscous ink and air bubbles are forcibly suctioned out from the suctioning opening within the cap via the suctioning opening and an ink suctioning member provided above the atmosphere communicating opening.
Subsequently, reverse rotating of the discharging roller causes the valve lever to open the valve rubber. Thus, the atmosphere communicating opening of the cap opens, and the pressure within the cap becomes that of the ambient atmosphere. Consequently, ink is no longer suctioned and discharged from the ink discharging orifices of the recording head, and further the residual ink within the cap is instantaneously discharged from the suctioning opening by the capillary action of the ink absorbing member. Also, the ink within the pump tube is also suctioned, and discharged from the ink discharging end of the pump tube. This action is called xe2x80x9cpneumatic suctioningxe2x80x9d. Subsequently, the PG motor stops, and the discharging roller rotates forward, thereby causing the cap to be distanced from the face of the recording head upon which are formed the ink discharging orifices, the capping is disengaged, and the valve lever closes the valve rubber. Thus, the series of actions for the suctioning recovery operation is completed.
Such conventional suction recovery devices still have the following problems.
As described above, in the suction recovery action, the ink suctioned out from the recording head is drawn to the suctioning opening within the cap by both the capillary action at the air holes of the ink absorbing member, and the negative pressure, and is thus discharged. The ink absorbing member is normally assembled into the bottom face within the cap, and the ink absorbing member has been prevented from rising upward by a ledge-shaped rising prevention member provided on the inner circumference wall of a rib configuring the perimeter of the cap.
However, the area to be capped by the cap is increasing due to the increase in ink discharging nozzles for color recording heads and high-quality high-resolution recording heads. Thus, the area of the ink absorbing member also increases, and the distance between the suctioning opening serving as the ink discharging opening within the cap and the ledge-shaped rising prevention member also tends to increase. Accordingly, deformation in the ink absorbing member and the cap and margin-of-error thereof in precision in manufacturing, have marked effects on the state of contact between the ink absorbing member and the suctioning opening, and there has been the possibility that the gap between these would spread.
In the state that gap between the ink absorbing member and the suctioning opening has spread, air flows in from the suctioning opening through this gap at the time of the above-described pneumatic suctioning more readily (i.e., air flows in from the atmosphere communicating opening and end of absorbing material), air is discharged from the suctioning opening in great amounts, resulting in a phenomena wherein ink existing within and upon the ink absorbing members not discharged but remains within.
In the event that ink remains within the cap, this means that a great amount of ink adheres to the recording head side at the time of opening the cap, so ink may splatter in great amounts at the time of the wiping action (an action wherein the discharging face is wiped with a wiping blade) normally performed following suctioning and soil the interior of the apparatus. Also, ink adhering to the discharging orifices of the recording head may lead to ink of a different color finding its way into the discharging orifices, resulting a mixed color phenomena wherein the image is printed with a color other than that intended.
Also, the ink absorbing member repeatedly swells and shrinks by 2 to 3% due to absorbing ink and drying, so the above-mentioned ledge-shaped rising prevention member alone is insufficient to position the absorbing material in a sure manner so that there is no deformation thereof, and the assembly state is unstable.
Accordingly, it is an object of the present invention to provide a cap for an ink-jet recording apparatus, and an ink-jet recording apparatus, wherein the ink absorbing member is tightly held in contact to the sealing space of the cap so as to not depart therefrom.
Also, it is another object of the present invention to provide a cap for an ink-jet recording apparatus, and an ink-jet recording apparatus, wherein the suctioning opening at the bottom face of the cap and the ink absorbing member can be constantly held in close contact in a secure manner.
According to one aspect of the present invention, provided are a cap, having a perimeter coming into contact with a discharging orifice face upon which a discharging orifice for discharging ink is provided, and a sealing space within the perimeter for covering the discharging orifice; an ink absorbing member provided in the sealing space; and a holding member for holding the ink absorbing member to prevent the ink absorbing member from being removed from the sealing space, provided within the sealing space at a position separated from the perimeter so as not to come into contact with the discharging orifice face when the perimeter of the cap is in contact with the discharging orifice face.
Also, according to another aspect, an ink-jet recording apparatus comprises: a recording head for recording images on recording media upon which an ink discharging orifice is provided; a cap, having a perimeter coming into contact with a discharging orifice face upon which a discharging orifice for discharging ink is provided, and a sealing space within the perimeter for covering the discharging orifice; an ink absorbing member provided in the sealing space; and a holding member for holding the ink absorbing member to prevent the ink absorbing member from being removed from the sealing space, provided within the sealing space at a position separated from the perimeter so as not to come into contact with the discharging orifice face when the perimeter of the cap is in contact with the discharging orifice face.
According to the present invention, a holding member is provided within the sealing space at a position separated from the perimeter so as not to come into contact with the discharging orifice face when the perimeter of the cap is in contact with the ink discharging orifice face, so the ink absorbing member can be securely held so as to not be removed from the sealing space, and also adverse effects on the ink discharging orifice face, such as re-adhering of ink and the like due to the holding member, can be prevented.
Also, positioning a holding member for securely holding the ink absorbing member against the bottom face of the cap near the suctioning opening allows the suctioning opening of the cap and the ink absorbing member to be held in close contact in a sure manner at all times, so even in the event that the cap is large, the effects of deformation in the ink absorbing member and the cap and margin-of-error thereof in precision in manufacturing on the state of contact between the ink absorbing member and the suctioning opening can be suppressed. Accordingly, air can be prevented from flowing into the suctioning opening, the phenomena wherein ink remains within the ink absorbing member within being discharged therefrom can be prevented at the time of opening the cap and so forth, and accordingly, mixing of colors due to ink adhering to the recording head and soiling of the inside of the apparatus due to splattering of the ink at the time of wiping, can be prevented.
Also, forming the holding member at a position not facing ink discharge orifices of the recording head allows the ink suctioned from the ink discharging orifices to be speedily absorbed by the ink absorbing member, thereby preventing mixing of colors at the discharging orifices due to ink staying around the ink discharging orifice face.
Also, configuring the holding member so as to not protrude above the upper face of the ink absorbing member in the state of the suctioning opening of the cap and the ink absorbing member being in contact prevents ink from adhering to the ink discharging orifice face in a more effective manner. Also, there is less necessity to consider the positional relation between the holding member and the ink discharging orifices, so the degree of freedom in placement is greater for both.
Also, providing an elastic member which deforms by contact with the ink absorbing member of the holding member at the point of contact with the ink absorbing member allows positional change of the ink absorbing member as to the cap to be restricted, so even in the event that the ink absorbing member repeatedly sells and shrinks due to absorbing ink and drying, the ink absorbing member can be positioned in a sure manner without causing deformation of the ink absorbing member, thereby stabilizing the assembly state of the ink absorbing member.
Also, forming the holding member or the elastic member integrally with the cap, with the same material as that of the cap, enables costs to be reduced.
Further, forming the elastic member of a rib having a cross-sectional form of a triangle with the apex thereof toward the ink absorbing member further facilitates deforming of the elastic member, and suppresses deformation of the ink absorbing member.
Further objects, features and advantages of the present invention will become apparent from the following description of the preferred embodiments with reference to the attached drawings.